JP2015010229A - Fluorinated polymer based coatings and methods for applying the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide fluorinated polymer based coatings and methods for applying the same.SOLUTION: A coating includes about 60 wt.% to about 90 wt.% of one or more fluorinated polymers, about 1 wt.% to about 7 wt.% of one or more erosion resistant fillers, about 3 wt.% to about 9 wt.% of one or more anticorrosive pigments, about 1 wt.% to about 4 wt.% of one or more thixotropic agents, and about 1 wt.% to about 4 wt.% of one or more porosity reducing filler materials.

Description

  The subject matter disclosed herein relates to coatings, and more particularly to fluorinated polymer-based coatings that can be applied to turbine compressor blades.

  In a gas turbine engine, a compressor section generally comprises a plurality of rows of compressor blades (also referred to as “rotor blades” or “rotor airfoils”) and stator blades (also referred to as “stator airfoils”). Includes steps. The compressor blades rotate around the rotor and thus impart kinetic energy to the air flow through the compressor. Immediately following the row of compressor blades is a row of stationary stator blades. The compressor blades and the stator blades can each operate in concert to turn the air flow to reduce the air velocity and increase the static pressure of the air flow through the compressor section. Multiple stages of compressor blades and stator blades can be stacked in an axial compressor to achieve the required discharge pressure ratio for inlet air. Therefore, the compressor and the stator blade can be fixed to the rotor wheel and the stator case by a dovetail or a root or base attachment, respectively.

  In operation, the compressor blades can be exposed to mechanical stresses and severe operating conditions due to the rotational speed of the compressor. These levels of stress, coupled with other operating conditions, can affect the level of erosion or corrosion experienced. For example, ambient air drawn through the compressor section can include components that can cause corrosion or wear to the compressor blades or other such components. Some components may also be exposed to mixtures of hydrocarbon-based lubricants, carbonaceous soot, earth and sand, rust, and the like.

  To provide additional protection from these elements, a coating such as polytetrafluoroethylene (PTFE) can be applied to an article such as a compressor blade. However, as the coating thickness increases, aerodynamic performance can be affected.

  Accordingly, alternative fluorinated coatings are desirable in the art.

US Pat. No. 7,992,823

  In one embodiment, a coating is disclosed. The coating comprises about 60% to about 90% by weight of one or more fluorinated polymers, about 3% to about 5% by weight of one or more erosion resistant fillers, about 5% to about 7% by weight. One or more anticorrosive pigments, from about 1% to about 4% by weight of one or more thixotropic agents, and from about 2% to about 3% by weight of one or more porosity reducing fillers.

  In another embodiment, a coated article is disclosed. The coated article includes a substrate element having an outer surface and a coating covering at least a portion of the outer surface of the substrate element. The coating comprises about 60% to about 90% by weight of one or more fluorinated polymers, about 1% to about 7% by weight of one or more erosion resistant fillers, about 3% to about 9% by weight. One or more anticorrosive pigments, about 1% to about 4% by weight of one or more thixotropic agents, and about 1% to about 4% by weight of one or more porosity reducing fillers.

  In yet another embodiment, a method for coating a substrate with a coating is disclosed. The method includes applying a coating on the outer surface of the substrate. The coating comprises about 60% to about 90% by weight of one or more fluorinated polymers, about 1% to about 7% by weight of one or more erosion resistant fillers, about 3% to about 9% by weight. One or more anticorrosive pigments, about 1% to about 4% by weight of one or more thixotropic agents, and about 1% to about 4% by weight of one or more porosity reducing fillers. The method further includes curing the coating on the outer surface of the substrate at a curing temperature of about 50 ° C to about 300 ° C.

  These and additional features provided by the embodiments discussed herein will be more fully understood in view of the following detailed description in conjunction with the accompanying drawings.

  The embodiments described in the drawings are merely exemplary and exemplary in nature and are not intended to limit the invention as defined by the claims. The following detailed description of illustrative embodiments can be understood when read in conjunction with the appended drawings, wherein like structure is indicated by like reference numerals.

1 is a schematic cross-sectional view of a coating on a substrate according to one or more embodiments shown and described herein. FIG. 1 is a schematic cross-sectional view of a coating on a substrate with a base coat in between according to one or more embodiments shown and described herein. FIG. 1 is a perspective view of a compressor blade with a coating according to one or more embodiments shown and described herein. FIG. 2 is an exemplary diagram of a coating method according to one or more embodiments shown and described herein. FIG.

  One or more specific embodiments of the present invention are described below. In order to provide a concise description of these embodiments, not all features of an actual implementation will be described here. As with any technology or design project, in developing any such actual implementation, to achieve specific developer goals that may vary from implementation to implementation, such as compliance with system and business-related constraints. It should be understood that a number of implementation specific decisions need to be made. Further, although such development efforts can be complex and time consuming, it should be understood by those of ordinary skill in the art having the benefit of this disclosure that it is a routine task of design, fabrication, and manufacturing.

  In describing elements of various embodiments of the present invention, what is written in the singular means that there is one or more of it. The terms “comprising”, “including”, and “having” are inclusive and mean that there may be additional elements other than the listed elements.

  A modified fluorinated polymer coating can be provided to protect the underlying substrate from various external forces and environmental conditions. In addition, the combination of selective additives and fluorinated polymers with a regular particle size distribution can provide a thin, smooth film with high adhesion to protect the substrate without impairing aerodynamic performance. it can. These coatings are used in both new manufactured articles or modified applications (eg, repairs) to allow longer and / or more efficient operating performance to be improved.

  Referring now to FIG. 1, a schematic cross-sectional view of a coated article 5 that includes at least one substrate 15 and a coating 10 is shown.

  The coating 10 can withstand high temperatures to protect the underlying substrate 15 while allowing at least sufficient operational performance, sufficient adhesion, porosity, surface roughness, and hydrophobic and oleophobic properties. Is formulated to have The coating generally comprises from about 60% to about 90% by weight of one or more fluorinated polymers, from about 1% to about 7% by weight of one or more erosion resistant fillers, from about 3% to about 9%. % By weight of one or more anticorrosive pigments, about 1% to about 4% by weight of one or more thixotropic agents, and about 1% to about 4% by weight of one or more porosity reducing fillers. Can do.

  The fluorinated polymer of the film 10 includes one or more fluorocarbon polymers. Specific examples of the fluorinated polymer include, but are not limited to, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy polymer), ETFE, (ethylenetetrafluoroethylene), PVDF (polyvinylidene fluoride), and PVF ( Polyvinyl fluoride). The one or more fluorinated polymers may comprise from about 60% to about 90% by weight of the film 10, or from about 70% to about 80% by weight of the film 10.

  The erosion resistant filler of the film 10 can include a material that improves the crack resistance of the entire film 10. Exemplary erosion resistant fillers include, but are not limited to, alumina, silica, boron carbide, silicon carbide, titania, tungsten carbide, aluminum nitride, boron nitride and silicon nitride. The one or more erosion resistant fillers may comprise from about 1% to about 7% by weight of the film 10, or from about 3% to about 5% by weight of the film 10.

  The anticorrosive pigment of the film 10 can include a material that helps prevent corrosion of the entire film 10. Exemplary anticorrosive pigments include, but are not limited to, zinc dust, zinc phosphate, iron sulfide, borates, precipitated silica, and titanium dioxide. The one or more anticorrosive pigments may comprise from about 3% to about 9% by weight of the film 10, or from about 5% to about 7% by weight of the film 10.

  The one or more thixotropic agents of the coating 10 can include a material that modifies the viscosity of the entire coating 10. Exemplary thixotropic agents include, but are not limited to, montmorillonite, mica and silica fume. The one or more thixotropic agents may comprise from about 1% to about 4% by weight of the film 10, or from about 2% to about 3% by weight of the film 10.

  The porosity reducing filler of the film 10 can include a filler that reduces the porosity of the entire film 10. Exemplary porosity reducing fillers include, but are not limited to, barium sulfate, calcium sulfate, talc and calcium carbonate. In certain embodiments, the reduced porosity filler may comprise one or more of the aforementioned fluorinated polymers, erosion resistant fillers, anticorrosive pigments and / or thixotropic agents. The one or more porosity reducing fillers may comprise from about 1% to about 4% by weight of the film 10, or from about 2% to about 3% by weight of the film 10.

  In certain embodiments, the coating 10 can include one or more additional materials. For example, the coating 10 can further include additional fillers including, but not limited to, carbon black. In certain embodiments, the coating 10 can further include molybdenum sulfide (such as about 5 wt% to about 10 wt%) to improve wear resistance. In certain embodiments, the coating 10 can include from about 2 wt% to about 5 wt% graphite or bronze granules for friction reduction. Further, in certain embodiments, the coating 10 can further include up to 10% by weight of ceramic nanoparticles to improve compressive strength. Although specific components are listed herein, it should be understood that these are non-limiting examples and that other materials may be included in addition or as alternatives.

  With further reference to FIG. 1, the coating 10 can include various thicknesses to protect the underlying substrate 15. For example, in certain embodiments, the coating 10 can be about 10 μm to about 60 μm thick. In certain embodiments, the coating 10 can include multiple layers. In some embodiments, each layer comprises about 60% to about 90% by weight of one or more fluorinated polymers, about 3% to about 5% by weight of one or more erosion resistant fillers, about 5% by weight. Up to about 7% by weight of one or more anticorrosive pigments, from about 1% to about 4% by weight of one or more thixotropic agents, and from about 2% to about 3% by weight of one or more porosity reducing fillers. Can be included.

  In some embodiments, the outer surface 17 of the substrate 15 can include a base alloy of its component itself such that the coating 10 is applied directly. However, referring now to FIG. 2, in one embodiment, the outer surface 17 of the substrate 15 is about 60% to about 90% by weight of one or more fluorinated polymers, as discussed above, about 3% to about 5% by weight of one or more erosion resistant fillers, about 5% to about 7% by weight of one or more anticorrosive pigments, about 1% to about 4% by weight of one or more Including one or more base coats 19 applied to the substrate 15 prior to applying the layer of coating 10 comprising a thixotropic agent and about 2 wt% to about 3 wt% of one or more porosity reducing fillers. Can do. The base coat 19 can include, for example, a coating that aids in the overall adhesion between the underlying substrate 15 and the subsequent coating 10.

  For example, the base coat 19 can include a material with galvanic compatibility with the substrate 15 so as to provide a support layer that provides protection if the subsequently applied coating 10 is lost during operation. The base coat in such embodiments can include, for example, a range of thickness from about 5 μm to about 20 μm.

  Further, in certain embodiments, the non-fluorinated polymer component of the coating can have a small particle size to aid in the functional properties of the entire coating. Specifically, erosion resistant fillers, anticorrosive pigments, thixotropic agents, and reduced porosity fillers can all have an average particle size in the nano-micron level range of about 50 μm or less. Further, the erosion resistant filler, anticorrosive pigment, thixotropic agent and porosity reducing filler can have a maximum individual particle size of about 100 μm or less. Combining these components having the particle size distribution described above provides multiple functional properties including hydrophobic and oleophobic while providing corrosion, erosion, and fouling resistance to the underlying substrate 15. The provided coating can be generated.

  For example, the coating 10 can withstand high temperatures during operation. “Tolerant” as used herein means that it does not show significant signs of degradation after prolonged exposure to high temperatures. In certain embodiments, the coating 10 can withstand a temperature of at least 300 ° C.

  Further, the coating can have a porosity of about 1% by volume or less and a surface roughness of about 5 Ra to about 20 Ra. The relatively low surface roughness can help meet the aerodynamic requirements of the underlying substrate 15, such as when the substrate 15 includes compressor blades for a turbine.

  As discussed above, the coating 10 can also be hydrophobic and oleophobic to help prevent residual accumulation of fluids such as water and oil. “Hydrophobic” refers to the physical properties of a water-repellent material. “Oleophobic” refers to the physical properties of an oleophobic material. Specifically, surfaces with low surface energy for fouling material (eg, water and / or oil) need to have a high contact angle and are wetted by fouling material or the fouling material has a low contact angle. Adhesion with fouling should be reduced on the surface. As used herein, the term “contact angle” is the angle formed by static droplets on the surface of a solid material. The higher the contact angle, the less liquid interaction with the surface. Therefore, when the contact angle with the surface of oil or other fouling material is high, it becomes more difficult for the fouling material to wet or adhere to the surface. For example, the coating can have a contact angle of about 90 degrees to about 140 degrees.

  The substrate 15 of the coated article can include a metal substrate 15 as utilized in a gas turbine. Metal substrates can include, but are not limited to, iron-based alloys (eg, stainless steel), nickel-based alloys, cobalt-based alloys, and the like. For example, referring now to FIG. 3, in one embodiment, the substrate can include a compressor blade 50. The compressor blade 50 can include an airfoil 52 that imparts kinetic energy to the air flowing through the compressor and base or root 53 as it rotates about the rotor. The airfoil 52 generally includes a suction surface 56 (ie, a convex surface) and a pressure surface 57 (ie, a concave surface).

The root 53 can include a platform 54 that is a radially outward surface of the root 53 from which an airfoil 52 extends. The platform 54 can be integrally joined to the root 53 of the compressor blade 50. Platform 54 defines a radially inner boundary for air flow over airfoil 52. As will be apparent to those skilled in the art, the root 53 further includes a dovetail that connects through complementary grooves in a rotor wheel (not shown) to secure the compressor blade 50 in place in the compressor. In general.

The substrate 15 (eg, the compressor blade 50) can include a coating 10 that covers at least a portion of the outer surface 17 (eg, the suction surface 56 and / or the pressure surface 57) to form the coated article 5. . Accordingly, the coating 10 of the coated article 5 has, as described above, about 60% to about 90% by weight of one or more fluorinated polymers, about 1% to about 7% by weight of one or more erosion resistances. About 3 wt% to about 9 wt% of one or more anticorrosive pigments, about 1 wt% to about 4 wt% of one or more thixotropic agents, and about 1 wt% to about 4 wt% of one The above porosity-reducing filler can be included.

  In embodiments where the substrate 15 includes a compressor blade 50, the compressor blade 50 may include an initial stage compressor blade 50. As used herein, “initial stage” refers to one of the first few stages of the compressor section in the entire turbine. Thus, in such an embodiment, the coating described herein can provide a thin coating having a smooth surface to protect the compressor blade 50 without significant impact on aerodynamics during operation. .

  The coating 10 can be applied to either a newly manufactured part or a service part for correction (for example, repair work or the like). Furthermore, the coating 10 can be applied to the substrate 15 on site or at a service facility. In some embodiments, the coating 10 can be applied directly to the substrate 15. In other embodiments, the coating 10 can be applied to one or more other coatings (e.g., base coats) already placed on the substrate 15.

  With reference now to FIG. 4 and with further reference to the structures illustrated in FIGS. 1-3, a method 100 for coating a substrate 15 with a coating 10 is illustrated. The method 100 may initially include applying a coating 10 on the outer surface 17 of the substrate 15 in step 110, the coating 10 being one or more of about 60% to about 90% by weight. About 1% to about 7% by weight of one or more erosion resistant fillers, about 3% to about 9% by weight of one or more anticorrosive pigments, about 1% to about 4% by weight % Of one or more thixotropic agents, and from about 1% to about 4% by weight of one or more porosity reducing fillers.

  The coating 10 applied in step 110 can be provided with a viscosity suitable to sufficiently cover the substrate 15 and remain in place before curing. For example, in certain embodiments, the coating 10 can have a viscosity of from about 0.1 Pa · second to about 0.15 Pa · second prior to curing, as understood herein.

  Application of the coating 10 in step 110 can be accomplished by any suitable means for covering the targeted area of the outer surface 17 of the substrate 15. For example, in some embodiments, the coating 10 can be applied at step 110 by dip coating, spray coating, brushing, and / or roll coating.

  The method 100 further includes, in step 120, curing the coating 10 on the outer surface of the substrate 15 at a curing temperature of about 50 ° C to about 300 ° C. The curing of step 120 may be performed for a time that provides sufficient bonding between the coating 10 and the substrate 15 and / or any layers therebetween, as well as time intervals, ramp rates, environmental conditions, and other combinations. it can.

  In certain embodiments, the method 100 may further include modifying the outer surface 17 of the substrate 15 at step 105 prior to applying the coating 10 of step 110. The modification of the outer surface 17 can include any treatment, preparation, or modification to the outer surface 17 that can enhance the promotion of adhesion with the subsequently applied coating 10. For example, the modification of the outer surface 17 may include a phosphating process, a blast cleaning process, a water jet, or the like. In other embodiments, the modification of the outer surface 17 can include applying a base coat 19 as understood herein.

  In certain embodiments, the method 100 can at least partially repeat one or more of the steps in which additional layers of such coating 10 are applied. The additional layer may also comprise about 60% to about 90% by weight of one or more fluorinated polymers, about 1% to about 7% by weight of one or more erosion resistant fillers, about 3% by weight. Up to about 9% by weight of one or more anticorrosive pigments, from about 1% to about 4% by weight of one or more thixotropic agents, and from about 1% to about 4% by weight of one or more porosity reducing fillers. Can be included. The additional layer can be further cured at the curing temperature to promote sufficient adhesion between the multiple layers of the coating 10.

  In some of these embodiments where multiple layers are applied, the curing temperature used for each additional curing step can be increased at incremental levels. For example, the curing temperature can be increased by at least about 15 ° C. and held for 15-30 minutes, then an additional layer can be applied, and similar curing temperature increases and holding times can be repeated. Such an embodiment can provide a plurality of thin coatings with improved cross-linking efficiency resulting in increased durability of the entire coating 10.

  It should be understood that a coating can be provided to protect the underlying substrate from various external forces and environmental conditions. Films embodying the compositions presented herein can seal the surface of the underlying substrate and help control the permeation of corrosive vapors and liquids. In addition, the coating is provided with a relatively thin layer having a smooth surface and can protect the part without significantly affecting the aerodynamic characteristics of the application.

  Although the invention has been described in detail with respect to only a limited number of embodiments, it is to be understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate many variations, modifications, substitutions, or equivalent arrangements not described above, which correspond to the spirit and scope of the invention. In addition, while various embodiments of the invention have been described, it is to be understood that aspects of the invention can include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

5 Coated article 10 Coating 15 Base material 17 Outer surface 19 Base coat

Claims (20)

  About 60% to about 90% by weight of one or more fluorinated polymers, about 1% to about 7% by weight of one or more erosion resistant fillers, about 3% to about 9% by weight of one A coating comprising the above anticorrosive pigment, from about 1% to about 4% by weight of one or more thixotropic agents, and from about 1% to about 4% by weight of one or more porosity reducing fillers.   The coating of claim 1, wherein the one or more fluorinated polymers are selected from the group consisting of polytetrafluoroethylene, perfluoroalkoxy polymers, ethylene tetrafluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride.   The coating of claim 1, wherein the one or more erosion resistant fillers are selected from the group consisting of alumina, silica, boron carbide, silicon carbide, titania, tungsten carbide, aluminum nitride, boron nitride and silicon nitride.   The coating according to claim 1, wherein the one or more anticorrosive pigments are selected from the group consisting of zinc dust, zinc phosphate, iron sulfide, borate, precipitated silica and titanium dioxide.   The coating according to claim 1, wherein the one or more thixotropic agents are selected from the group consisting of montmorillonite, mica and silica fume.   The coating according to claim 1, wherein the one or more porosity reducing fillers are selected from the group consisting of barium sulfate, calcium sulfate, talc and calcium carbonate.   The coating of claim 1, wherein the coating is about 10 μm to about 60 μm thick.   A plurality of layers, wherein each layer is about 60% to about 90% by weight of one or more fluorinated polymers, about 1% to about 7% by weight of one or more erosion resistant fillers, about 3% by weight; % To about 9% by weight of one or more anticorrosive pigments, about 1% to about 4% by weight of one or more thixotropic agents, and about 1% to about 4% by weight of one or more porosity reducing fillings. The coating according to claim 1, comprising a material.   The coating of claim 1 wherein the erosion resistant filler, anticorrosive pigment, thixotropic agent and porosity reducing filler all have an average particle size of about 50 µm or less and a maximum individual particle size of about 100 µm or less.   The coating of claim 1, wherein the coating withstands a temperature of at least 300 ° C.   The coating according to claim 1, wherein the porosity of the coating is about 1% by volume or less.   The coating according to claim 1, wherein the coating has a surface roughness of about 5 Ra to about 20 Ra.   The coating of claim 1, wherein the coating is hydrophobic and oleophobic such that it has a contact angle of about 90 degrees to about 140 degrees. A coated article,
A substrate element having an outer surface;
A coating covering at least a portion of the outer surface of the substrate element;
From about 60% to about 90% by weight of one or more fluorinated polymers, from about 1% to about 7% by weight of one or more erosion resistant fillers, from about 3% to about 9%. % By weight of one or more anticorrosive pigments, from about 1% to about 4% by weight of one or more thixotropic agents, and from about 1% to about 4% by weight of one or more porosity reducing fillers, Coated articles.   The coated article of claim 14, wherein the substrate element comprises a compressor blade for a turbine.   The coated article of claim 14, wherein the outer surface of the substrate includes a base coat and the coating covers at least a portion of the base coat. A method of coating a substrate with a film,
Applying a coating on the outer surface of the substrate;
Curing the coating on the outer surface of the substrate at a curing temperature of about 50 ° C. to about 300 ° C .;
From about 60% to about 90% by weight of one or more fluorinated polymers, from about 1% to about 7% by weight of one or more erosion resistant fillers, from about 3% to about 9%. % By weight of one or more anticorrosive pigments, from about 1% to about 4% by weight of one or more thixotropic agents, and from about 1% to about 4% by weight of one or more porosity reducing fillers, Method.   The method of claim 17, wherein the coating has a viscosity of from about 0.1 Pa · second to about 0.15 Pa · second prior to curing.   Applying an additional layer of coating, wherein the additional layer of coating is from about 60% to about 90% by weight of one or more fluorinated polymers, from about 1% to about 7% by weight of one or more. Erosion resistant filler, about 3% to about 9% by weight of one or more anticorrosive pigments, about 1% to about 4% by weight of one or more thixotropic agents, and about 1% to about 4% by weight. 18. The method of claim 17, comprising one or more fillers.   20. The method of claim 19, wherein the additional cure temperature is higher than the initial cure temperature.